1. Field of the Invention
The present invention relates to a shroud for a gas turbine engine. More particularly, the present invention relates to an inner liner for a shroud for a gas turbine engine. Still more particularly, the present invention relates to an inner graphitic carbon liner that is received in a shroud of a gas turbine engine to reduce the overall engine weight and cost and vane trunnion wear.
2. Description of Prior Art
The operating environment for a turbofan engine and its various component is extremely harsh. The vibrations due to normal use at operating speeds are extreme. The operating temperature of some of the components are also extremely high. One of the many components that may experience wear in the engine due to vibrations and high temperature are the variable vanes' inner trunnions.
Currently, the trunnions are encased within a carbon steel split bushing. The split bushing is secured between a carbon steel split inner shroud. During wear, the carbon steel bushing and carbon steel split liner vibrate against one another and cause considerable wear on the vane's inner diameter trunnion encased in the bushing. The wear on the trunnion reduces the lifecycle of the trunnion and increases maintenance time and expense due to required replacement/refurbishment of the entire vane.
Therefore there exists a need for a shroud that can receive a sacrificial graphitic carbon liner to hold a vane trunnion, thereby reducing trunnion replacement/refurbishment costs, overall engine weight and cost of ownership and maintenance.